1. Field of the Invention
Embodiments of the present invention relate to a semiconductor device that includes a plurality of semiconductor modules including, for example, a power device and a method for manufacturing a semiconductor device.
2. Discussion of the Background
A power conversion inverter device has been widely used as one of power conversion devices. For example, an electric motor is generally used as a driving source of an electric vehicle, a hybrid vehicle, or the like. An inverter device is generally used to control various types of motors. As the power conversion device, a semiconductor module is used in which a power device, such as an insulated gate bipolar transistor (IGBT) or a free-wheeling diode (FWD), is sealed in a predetermined shape with a mold resin material. A plurality of semiconductor modules are combined to form a power conversion device.
A module-type electric device block has been proposed which includes a mutual coupling means. In the module-type electric device block, when two module-type blocks, such as mold cases which surround an electric device, are arranged and connected to each other, the two mold cases are coupled in a hinged manner. When one of the two cases is pivoted to come into contact with the other case, a protruding end of a tongue-shaped portion which is provided in one case is fitted to the outer surface of the other case to couple the two mold cases (for example, see JP 62-86900 A) (“Patent Document 1”).
As another attachment method, an inverter device has been proposed in which six main switching elements, which are modules forming one arm of the inverter device, are prepared, are divided into three sets each having two main switching elements, and the main switching elements in each set are connected by a U-phase main circuit board, a V-phase main circuit board, and a W-phase main circuit board (for example, see JP 3430192 B1) (“Patent Document 2”).
As another attachment method, a semiconductor device has been proposed in which three semiconductor modules are mounted on the upper surface of a heat sink, a reinforcing beam is arranged on the upper surface of the semiconductor module, with a leaf spring which traverses each semiconductor module interposed therebetween, and screws are inserted from the upper side of the reinforcing beam to the heat sink through the leaf spring and the semiconductor module to fix the three semiconductor module to the heat sink (for example, see JP 4129027 B1) (“Patent Document 3”).
A semiconductor device has been proposed in which three columns of semiconductor device units in which a semiconductor chip is sealed with a resin, each column having two semiconductor device units, are arranged on a cooler; bolt tightening units are provided at both ends of each semiconductor device unit in the row direction; a wiring substrate is arranged on the upper surfaces of each semiconductor device unit and each bolt fastening unit; and bolts are inserted into the cooler through the bolt tightening units from the upper side of the wiring substrate to fix the semiconductor device units to the cooler (for example, see WO 2011/083737 A) (“Patent Document 4”).
However, in some cases, in order to respond to various requests, such as current capacity or a circuit structure, a plurality of semiconductor modules are combined with each other and arranged to respond to desired current capacity or circuit structure. For these requests, in the related art disclosed in Patent Document 1, two mold cases having the electric devices are coupled to each other by the mutual coupling means including the hinge portion and the tongue-shaped portion. However, in this case, the electrical connection between the two mold cases is not considered at all and there is an unsolved problem that the device cannot be applied as a power conversion semiconductor device.
In the related art disclosed in Patent Document 2, three main elements for an upper arm and three main elements for a lower arm, which form the inverter device, are individually screwed to the radiation fin, the individual main circuit boards are mounted on the upper surfaces of the corresponding main elements for an upper arm and the corresponding main elements for a lower arm, and the terminal portions are fixed to each other by screws. Therefore, when the inverter device is formed, two screwing processes, that is, a process of screwing the main elements to the radiation fin and a process of screwing the main circuit boards to the upper surfaces of each main element for an upper arm and each main element for a lower arm are required and there is an unsolved problem that it takes a lot of time for the attachment operation.
In the related art disclosed in Patent Document 3, three semiconductor modules, the leaf spring for pressure, and the reinforcing beam are arranged on the heat sink and are fixed to the heat sink by the common bolts. Therefore, the leaf spring for pressure and the reinforcing beam are required to bring a plurality of semiconductor modules into close contact with the heat sink and it is difficult to position the semiconductor modules, the leaf spring for pressure, the reinforcing beam, and the female screws of the heat sink when the bolts are tightened. In addition, since the user needs to perform the attachment operation, there is an unsolved problem that assemblability deteriorates. In addition, when the plurality of semiconductor modules and the heat sink are supplied while being attached to each other, there is an unsolved problem that the versatility of the semiconductor module is reduced and the semiconductor module is used only for a specific use.
In the related art disclosed in Patent Document 4, six semiconductor device units are interposed between the bolt fastening units, the wiring substrate covers the semiconductor device units and the bolt fastening units, with an elastic body interposed therebetween, and the bolts are inserted into the cooler through the bolt fastening units from the upper side of four corners of the wiring substrate to fix the semiconductor device units to the cooler. Therefore, there is an advantage that stress which occurs when the bolts are tightened is applied only to the bolt fastening units and is not applied to the semiconductor device units. However, since the six semiconductor device units are not directly fixed to the cooler, there is an unsolved problem that it is difficult to ensure the reliable contact between the semiconductor device units and the cooler.
Patent Document 1 to Patent Document 4 do not disclose a technique which flexibly responds to current capacity or a circuit structure or a technique which mounts a plurality of semiconductor chips in one semiconductor module in order to improve capacity.